Synergistic catalytic degradation of crystal violet dye and ciprofloxacin drug using g-C3N4/CuO nanocomposites under visible light

• Green synthesised CuO NPs incorporated into g-C 3 N 4 effectively degrade crystal violet dye and ciprofloxacin drug. • Graphitic carbon nitride with 20% copper oxide achieves 96% dye and 93% drug degradation under visible light. • Enhanced charge transfer and reduced recombination improve photocatalytic efficiency. • Degradation products are non-toxic to aquatic species, ensuring environmental safety. • The synthesized photocatalyst demonstrated high stability and recyclability for up to 4 cycles. Photocatalytic water purification using semiconductor photocatalysts offers a promising solution to global environmental challenges. In this study, we synthesized pristine CuO nanoparticles (NPs), graphitic carbon nitride (g-C 3 N 4 ), and CuO-incorporated g-C 3 N 4 nanocomposites with varying weight percentages of CuO NPs for the photocatalytic degradation of crystal violet (CV) dye and ciprofloxacin (CIP) drug. Characterization of the prepared samples revealed that the incorporation of CuO NPs into g-C 3 N 4 significantly altered their energy bandgap, morphology, and photocatalytic efficiency. The interfacial contact between CuO and g-C 3 N 4 was confirmed by zeta potential analysis and transmission electron microscopy (TEM), with CuO NPs having an average size of 47 nm. The incorporation of CuO NPs into g-C 3 N 4 resulted in lower photoluminescence (PL) intensity, which suggests enhanced charge transfer and reduced charge recombination compared to pristine g-C 3 N 4 . Notably, g-C 3 N 4 doped with 20 wt% CuO NPs demonstrated superior photocatalytic degradation of CV (96 %) and CIP (93 %) after 80 and 70 min of visible light irradiation, respectively. All samples adhered to pseudo-first-order rate kinetics for CV and CIP degradation and exhibited good recyclability over up to four cycles. The toxicity of the degradation products was evaluated using ECOSAR software. The enhanced photocatalytic performance of g-C 3 N 4 /CuO-20 can be attributed to its synergistic effect and the effective suppression of e − /h + pair recombination, compared to pristine g-C 3 N 4 . Therefore, g-C 3 N 4 /CuO nanocomposites represent a promising approach for wastewater treatment.